Run results for: For in vs Object.keys.forEach vs. Object.keys+for

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.114 Safari/537.36

Browser: Chrome 89

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
For In	851.8 Ops/sec
Object keys forEach	1214.3 Ops/sec
For(;;) over Object.keys using keys.length	785.8 Ops/sec

Script Preparation code:

var obj = new Object()
var keys = (new Array(100)).fill(0).map((x, i) => { return i + 1 })
keys.forEach((x) => { obj['prop' + x] = x })

Tests:

For In
for (var key in obj) { if (obj.hasOwnProperty(key)) console.log(obj[key]) }
Object keys forEach
Object.keys(obj).forEach(key => console.log(obj[key]))
For(;;) over Object.keys using keys.length
for (let i = 0, keys = Object.keys(obj); i < keys.length; i++) { console.log(obj[keys[i]]); }